Method for treating heat cured tobacco



Aug. 2, 1955 P. F; JACKSON 2,714,385

METHOD FOR TREATING HEAT CURED TOBACCO Filed April 2, 1951 6 Sheets-Sheet 1 FIG. lb Wm IN VENTOR P ETER F. JACKSON BY gm u h ATTORNEYS,

Aug. 2', 1955 P. F. JACKSON 2,714,335

METHOD FOR TREATING HEAT CURED TOBACCO Filed April 2, 1951 e Sheets-Sheet 2 F I 60 3' 5' iii INVENTOR PETER F. JACKSON ATTORNEYS g- 1955 P. F. JACKSON METHOD FOR TREATING HEAT CURED TOBACCO 6 Sheets-Sheet 3 Filed April 2, 1951 R mN mm mK m J F" R E T E P 4 4 1 m Aug. 2, 1955 P. F. JACKSON METHOD FOR TREATING HEAT CURED TOBACCO 6 Sheets-Sheet 4 Filed April 2, 1951 INVENTOR PETER E JACKSON BY A I A553???- Aug. 2, 1955 P. F. JACKSON 2,714,385

METHOD FOR TREATING HEAT CURED TOBACCO Filed April 2, 1951 6 Sheets-Sheet 5 INVENTOR PETER F. JACKSON ATTORNEYS,

Aug. 2, 1955 P. F. JACKSON 2,714,385

METHOD FOR TREATING HEAT CURED TOBACCO Filed April 2, 1951 6 Sheets-Sheet 6 FIG.T.-

FIG. 8.

INVENTOR PETER E JACKSON ATTORNEYS,

United states Patent METHQD FOR TREATING HEAT CURED TGBACCO Peter F. Jackson, Henderson, N. C.

Application April 2, 1951, Serial No. 218,799

Claims. (Cl. 131-140) In the usual commercial practice, tobacco is delivered 1.

by the grower or farmer to a warehouse or dealer, where the tobacco is sold at auction. As it appears on the warehouse floor, the tobacco, usually contained in baskets or the like, is in the form of hands, and is usually quite dry and brittle, the moisture content being in the neighborhood of 18-20%. It the tobacco has not been heat cured in the barn, but rather allowed to cure slowly without application of artificial heat, as is the case for example in the tobacco growing areas of Maryland, the

tobacco from the warehouse floor is packed substantially without further treatment. On the other hand, if the tobacco has been heat cured, as in a barn by the action of artificial heat from a fine system or oil burners, according to the practice in the Carolinas, the stems or butts of the hands are moist, though the leaves themselves are relatively dry, and it is necessary to take the tobacco from the warehouse floor and subject it to re-drying and ordering before packing.

According to the common commercial practice of redrying, the hands of tobacco are usually mechanically or manually shaken in order to at least partly open the leaves of the hands. The hands are then placed on sticks and passed through a drying kiln in which the moisture content of the tobacco is reduced to about 9%. The tobacco is then ordered, as by treatment with live steam,

to bring the moisture content up to about 11% uniformly M throughout the hands, and the ordered tobacco can then be packed in hogsheads or the like without breakage of the leaves. As taken from the warehouse, the hands of tobacco are tight, that is,.the leaves of the hand are bunched closely together. In this compact relation resulting from being compressed together while intially green, the leaves have become somewhat dry and their irregularities cause adjacent leaves to resist separation.

My treatment causes the leaves to soften and become 4;

smoother, whereby the leaves are separable and the enof higher grade tobacco is prevented. Futrher, my invention results in speeding up the re-drying operation, and provides a final product of greatly improved quality.

In accordance with my invention, the hands of tobacco are placed directly upon the usual tobacco sticks without any preliminary shaking whatsoever, and the tobacco is then treated with dry heated air in a manner resulting in simultaneous opening or loosening of the hands and partial drying thereof. Treatment of the hands with dry heated air in accordance with my invention results in a softening and smoothing of the tobacco leaves, the leaves thus becoming less brittle. This changed quality of the leaves, resulting from treatment with dry heated air, is not the result which would be expected. The expected result would be increased stifiness, without any opening or loosening of the leaves in the hand. But, to the;contrary, the leaves are rendered pliant and flaccid and free from any tendency to cling together, so that they are in the best possible loosened condition when subjected to the usual treatment in the redryer. Whereas the leaves in the tobacco hands as ordinarily received at the .re-drying plant are more or less closely bunched and crimped together and are relatively stiff and brittle, the method of the present invention not only softens the leaves and makes them freely separable from each other without damage to the leaves, but such conditioning also extends through the entire length of the leaves in the hand.

In order that the invention may be understood in detail, reference is had to the acompanying drawings which form a part of this specification and wherein:

Figs. 1, 1a and lb are diagrams illustrating successive steps of my tobacco treating method;

Fig. 2 is a perspective view showing the manner in which a stick of tobacco hands is carried by a pair of spaced parallel endless conveyor chains in accordance with the invention;

Fig. .3 is a front elevational view of a tobacco treating apparatus constructed in accordance with the invention;

Fig. 4 is a top view of the apparatus shown in Fig. 3, a portion of the casing being broken away;

Fig. 5 is a side elevational view of the apparatus illustrated in Fig. 3, a portion of the casing being broken away;

Fig. 6 is a diagrammatic side elevation of certain of the parts of the apparatus shown in Fig. 3, illustrating the manner in which heated air flows within the apparatus;

Fig. 7 is a detail sectional view taken on the line 7--7, Fig. 3, parts being shown in elevation;

Fig. 8 is a detail sectional view taken on the line 8-8, Fig. 3, parts being shown in elevation;

Fig. 9 is a detail elevational view illustrating one form of conveyor chain which may be employed in the apparatus, and

Fig. 10 is a diagrammatic view showing the relation between the apparatus of my invention and a conventional tobacco drying kiln with which the apparatus is used.

tire hand more open. If the leaves of the hands are not loosened, as by the conventional manual or mechanical shaking operation, the re-drying and ordering steps are materially impeded. However, the mechanical shaking operation has two major disadvantages. First, either too much manual labor is required, or complex mechanical shaking conveyors must be employed. Second, shaking of the hands, which usually must be quite vigorous, results in breakage of the leaves and considerable loss of high grade tobacco.

My invention provides a novel method for pre-treating hands of tobacco which are to be re-dried and ordered. According to the invention, the usual manual or mechanical shaking step is entirely eliminated, so that a considerable labor cost is saved and a very material loss n I have found that a dry hand of completely cured and tightly bunched tobacco may be loosened. with the leaves limp and pliant from stem to tip, solely by the action of heated dry air. According to my invention, the hand is suspended with the leaf tips pointing downwardly and the stem upwardly, and the hand thus suspended is subjected successively to the actions of two currents of heated dry air, one current flowing upwardly into and about the hand, from the leaf tips to the stem thereof, and the other current flowing downwardly from the stem to the leaf tips. Preferably, the hand is moved along transversely to its length, first through the upwardly cirected current of air and then through the downwardly directed current of air. The leaves of the hand before treatment are relatively still and closely bunched; after the treatment just described the leaves hang freely in a loose, pliant condition, so that conditioning action in the re-drying" step may affect the entire surface of each leaf throughout the hand to an extent which would not have been possible if the leaves were stiff and crimped together. Y

The precise conditions of the operation for any one batch of tobacco will depend upon the condition of the tobacco. As a general rule, the temperature of the air should be within the, range of 160200 F. I The air should be dry in the sense that it is unsaturated and will therefore take up moisture, and in this respect the present invention must be contrasted to prior proposals for pretreating tobacco with steam or moist air. Preferably, in my process, the heated air should be below 30% relative humidity.v

Ordinarily, I prefer to support the hands on the usual tobacco sticks and carry the sticks through the currents of heated dry air by means of a conveyor. Thus, the speed of the conveyor may be selected to maintain the hands within the area of the heated dry air for the proper time. In a preferred practice of the invention, the two currents of heated dry air are immediately adjacent, providing an area of heated air extending for about eight feet in the direction of travel of the tobacco, and the rate of travel of the tobacco is made to be about feet per minute. Thus, each hand of tobacco remains in contact with the heated dry air for about seconds. When a hand of tobacco is treated in this manner, I find that the hands are loosened and the leaves are softened, become smoother and are somewhat separated, and that the resulting condition is superior to that which can be obtained by manual shaking. After the hand has been subjected to the currents of heated dry air as just described, the hand can be carried directly into the redryer. Further, the preliminary treatment with heated dry air reduces the moisture content of the tobacco, although at the same time the leaves are rendered less fragile, so that the time required for the re-drying operation is materially reduced. The time in the redryer is less because the opened condition of the treated hands renders the redryer action more effective. All manual operations ordinarily required for opening the hand are eliminated by my process and, since the speed of the conveyor in the drying kiln can be increased, both because of the preliminary drying effect of my method and because the tobacco hands are opened into a better condition for drying than can be done by mechanical shaking, the number of man-hours required for the total redrying operation is considerably reduced. In actual practice with one particular drying plant handling tobacco cured in the Henderson area of North Carolina, I have found that this method has reduced the number of manhours required during one year of operation from 70,000 to 56,000, while the amount of tobacco handled was increased 15% and the quality of the treated tobacco was improved.

The manner in which I may practice my tobacco treating method is illustrated more precisely in Figs. 1, 1a and lb. The hand of tobacco 10 is placed upon a tobacco stick 11 in the conventional manner, with the leaf tips 10' thereof extending downwardly and the stem 10 extending upwardly. As shown in Fig. 1, the hand, when first placed upon the stick 11, is bunched tightly together. With the hand 10 suspended as just explained, a current of heated dry air is directed upwardly about the hand, as illustrated in Fig. la. This may be accomplished by moving the hand 10 over an impeller 12, the impeller being arranged to direct air upwardly first across a heating element 13 of any conventional type and then upwardly into the lower end of and about the hand of tobacco. After being subjected to the upward current of dry heated air, the tobacco is then subjected to a similar downward current, as shown in Fig. lb. This may be accomplished by moving the tobacco below an impeller 14, which forces the air downwardly'first across a suitable heating element 15 and then downwardly lengthwise of the hand 10 from the stem 10 to the tip 10.

Of course, in commercial practice, a plurality of the hands 10 are supported upon each stick 11, and the sticks are supported by spaced parallel conveyors. For example, the sticks may be carried by spaced endless conveyor chains 16 and 17, extending over sprocket wheels 18 and 19, as seen in Fig. 2. A commercial apparatus to carry out the method of my invention will ordinarily be associated directly with a horizontal re-drying kiln, and it is preferable that, as seen in Fig. 10, the endless conveyor extend continuously through the conventional redrying kiln K and a pre-treating chamber P constructed in accordance with my invention. The construction of horizontal kilns for re-drying tobacco is well known, usually involving a pair of parallel spaced endless conveyor chains 16 and 17 for carrying the tobacco sticks, and an endless conveyor belt 20 of relatively fine wire mesh or the like located in the kiln below the run of the tobacco to collect any fragments falling from the hands. As seen in Fig. 9, each link 21 of the conveyor chains may include a hook 22 to engage the tobacco stick at the end thereof, and a guide roller 23 is provided at the pivot point between each link.

Referring now to Figs. 3-5, a preferred form of apparatus for performing my invention will be described. As best seen in Figs. 4 and 5, the forward end of the conventional re-drying kiln K is joined at 24 to a generally rectangular casing or enclosure 25, the spaced parallel endless conveyor chains 16 and 17 of the kiln being extended entirely through the casing 25 and running over the sprocket wheels 18 and 19. The sprocket wheels 18 and 19 are carried by freely rotatable shafts 30 and 31, respectively, journalled in bearing plates 32 and 33, respectively, these bearing plates being mounted on bearing stands 34 and 35 secured to the front surfaces of the forward vertical frame members 27. Horizontal top frame members 26 are supported at their forward ends by the vertical members 27, and extend rearwardly to the kiln K. Similar horizontal bottom frame members, which may rest directly upon the floor of the drying room, extend beneath the top frame members 26, and the top and bottom frame members are interconnected to vertical braces 27. To the rear of the front frame members 27, sheet metal sides 28 are secured to the braces 27', and a sheet metal top closure extends between the two central top frame members 26, as seen in Fig. 4. A partial front closure 36 to confine the heated air, extending from the top of the chamber 25 to a point somewhat above the top runs of the conveyor chains 18 and 19, as seen in Fig. 3, is secured to the forward surfaces of the braces 27, and hinged to this front closure is a drop closure 37 to help confine the heated air and which may be lowered between the conveyor chains, or secured in raised position, as shown, by a hook and eye 38.

Thus, the chamber 25 comprises an enclosure joined at the back to the re-drying kiln K and open at the front for the admission of sticks of tobacco supported on the two endless conveyor chains.

Positioned just within the enclosure 25 at the forward end thereof is a vertical hot air blower unit 39 supported on the floor by legs 40. This blower may be of any conventional type capable of heating air and directing the same upwardly between the conveyors 16 and 17. Preferably, I employ a hot air blower of the type shown and described in United States Patent 2,300,574 to Iepertinger, granted November 3, 1942, and comprising a steam coil provided with heat exchange fins, a fan or impeller driven by an electric motor for passing air over the steam coil, and louvers for directing the discharge of heated air. Steam is supplied to the heat exchanger 39 of the blower unit 39 by a pipe 41, and the condensate is discharged through a pipe 42 provided with a steam trap 43. As seen in Fig. 7, when the blower 39 is in place in the casing 25, there is provided an upright sheet metal closure 44 in front of the blower unit, and a screen overlies the blower to prevent fragments of tobacco from falling upon the heat exchange unit of the blower, the screen 45 preferably being mounted upon the closure 44. Thus, hands of tobacco depending from sticks supported upon the chains 16 and 17 may pass freely over the blower unit 39, even should a hand he so long as to contact the forward edge of the blower unit. From Figs. 4, 5 and 7, it will be noted that the blower unit 39 is positioned immediately in front of the forward end of the collecting conveyor 20 of the re-drying kiln K.

Mounted in the top 29 of the casing 25, as seen in Fig. 8, and spaced rearwardly from the blower unit 39, that is, spaced in thedirection of travel of the tobacco being treated, is a second blower unit 46. This blower is of the same type as the blower unit 39, but is positioned to project heated air downwardly between the conveyor chains 16 and 17. Steam is supplied to the heat exchanger 47 of the blower unit 46 by means of a supply pipe 48, and

the condensate is discharged through a pipe 49 connected 5 to the discharge pipe 42 of the lower blower unit 39. The steam supply pipes 41 and 48 are connected to a main supply line 50 controlled by a weight operated valve 51 Both of the blower units take realtively cool air from the drying room in which the kiln is located, the lower blower unit 39 drawing air upward from the floor and the upper blower unit drawing air downwardly from above the casing 25. Air in the room will normally be at a temperature of 80 F. the two blowers is maintained such as to raise the temperature of the air to 160200 R, then the relative humidity of the air discharged from the blowers will be about l823%, and I have found these conditions to be ideal.

Below and slightly to the rear of the upper blower unit 46, beneath the conveyors 16 and 17, an exhaust opening 52, Fig. 5, is provided in one side of the casing 25. This opening communicates with the interior of a stack 53 and thence with a flue 54 extending through the roof of the building in which the kiln is located. The manner in which the heated air flows within the casing is illustrated in Fig. 6. Here it will be seen that air is directed upwardly by the blower unit 39, passing across the heat exchanger 39' thereof, and flowing upwardly past the tobacco sticks 11 (carried by the conveyors 16 and 17, Fig. 4). Simultaneously, air is directed downwardly by the blower unit 46, being heated by the heat exchanger 47 and travelling down past the tobacco sticks 11 toward the exhaust opening 52. Were it not for the downward current of air from the upper blower unit 46, the upward current of air from i the blower 39 would merely travel to the top of the casing and mushroom out across the under surface of the top 29. But, because of the upper blower, this upwardly travelling current of air is drawn rearwardly and then downwardly, into the stream from the upper blower 46, and thence carried to the exhaust opening 52, into the stack 53 and out through the flue 54. Thus, substantially all of the heated air which has contacted the tobacco is exhausted from the casing 25.

In order to determine the temperature within the casing 25, I provide a thermometer 55, Figs. 4 and 6, having its temperature sensitive portion located within the casing and its indicating scale arranged on the outside of the sidewall 28. The fan motors and the conveyor motors are electrically powered, and the controls are preferably grouped in a single control panel 56, Fig. 5, so that the speed of the motors can readily be changed should the conditions of operation vary.

In operation, the hands of tobacco are placed upon the sticks 10 without any preliminary treatment and the sticks are then loaded onto the conveyor chains 16 and 17 in the manner shown in Fig. 2. This operation is continuous, the conveyor chains operating to carry the tobacco through the chamber 25 and thence into the re- If the steam temperature in drying kiln K. Within the chamber 25, the tobacco hands are first contacted by dry heated air flowing upwardly from the blower 39, and then by the dry heated air flowing downwardly from the blower 46. When the hands are carried into the kiln K, they will be in fully loosened condition, ready for the drying operation. Also, their moisture content will have been considerably reduced by the action of the dry heated air, so that the speed with which they are moved through the kiln can be relatively high, as compared with the speed possible if the invention were not employed.

I claim:

1. The method of rendering limp, loose, and pliant the leaves of tightly bunched relatively dry hands of complately heat cured tobacco to be subjected to redrying, comprising suspending such hands, in the tightly bunched condition in which they are presented for redrying, with the leaf tips extending downwardly while avoiding shaking the hands, and directing a current of hot dry air at a temperature of -200 F. and a relative humidity of less than 30% upwardly into and about the suspended hands.

2. A method for treating hands of heat cured tobacco in the condition in which the cured hands are delivered by the farmer to the dealer, the leaves of such hands being closely bunched or mashed together so that the hands are unsuitable for direct redrying treatment, comprising suspending the hands in such condition with the leaf tips extending downwardly while avoiding shaking the hands, directing a current of hot dry air at a temperature of l60-200 F. and a relative humidity of less than 30% upwardly into and about the hands from the tips to the stems thereof, whereby the leaves of the hands are caused to become limp, loose, and pliant, and then subjecting the hands so treated to redrying.

3. A method for treating hands of heat cured tobacco in the condition in which the cured hands are delivered by the farmer to the dealer, the leaves of such hands being closely bunched or mashed together so as to be unsuitable for redrying, comprising vertically suspending the hands in such condition with the leaf tips extending downwardly while avoiding shaking of the hands to separate the leaves or open the hands, directing a current of hot dry air at a temperature of 160-200 F. and a relative humidity of less than 30% upwardly into and about the hands from the tips to the stems thereof, and then directing a current of hot dry air at a temperature of 160200 F. and a relative humidity of less than 30% downwardly about the hands from the stems to the tips thereof, whereby the leaves of the hands are caused to become limp, loose, and pliant so that the hands may be subjected to redrying without the necessity of a shaking operation.

4. A method for treating hands of heat cured tobacco in the condition in which the cured hands are delivered by the farmer to the dealer, the leaves of such hands being closely bunched or mashed together so as to be unsuitable for redrying, comprising vertically suspending the hands in such condition with the leaf tips extending downwardly while avoiding shaking of the hands to separate the leaves or open the hands, directing a current of hot dry air at a temperature of 160-200" F. and a relative humidity of less than 30% upwardly into and about the hands from the tips to the stems: thereof, and then directing a current of hot dry air downwardly about the hands, from the stems to the tips thereof, whereby the leaves of the hands are caused to become limp, loose, and pliant, and, finally, subjecting the hands to redrying without the necessity of first shaking the hands to prepare them for redrying.

5. A method for treating hands of heat cured tobacco in the condition in which the cured hands are delivered by the farmer to the dealer, the leaves of such hands being closely bunched or mashed together so as to be unsuitable for redrying, comprising establishing an up- 7 wardly flowing column of hot dry air having a temperature of 160-200 F. and a relative humidity of less than 30%, suspending the hands vertically with the leaf tips extending downwardly, and moving the hands of tobacco transversely of their length, while avoiding shaking of the hands, through said upwardly flowing column of air and then to a redrying zone, whereby said column of air is caused to flow upwardly into and about the hands and the leaves of the hands are caused to become limp, loose, and pliant before being subjected to redrying 130,695 Bowdon Aug. 20, 1872 Schwartz Nov. 21, Vaughan Feb. 20, Benjamin Aug. 15, Oatley Aug. 24, Wenusch Feb. 2, Harris Ian. 4, Touton June 21, Touton Mar. 28, Bogaty Jan. 21, Mosley et a1. -2 Feb. 2, Touton Mar. 7, Touton Apr. 1, Kirkpatrick Dec. 7, Moore July 5, 

